Although legacy (copper) wirelines have served as a principal information transport backbone for a variety of telecommunication networks, the continued development of other types of signal transport technologies, particularly those capable of relatively wideband service, including coaxial cable, fiber optic and wireless (e.g., radio) systems, have resulted in a multiplicity of systems that serve a diversity of environments and users, such as ISM (Industrial, Scientific and Medical) customers. A particular advantage of wireless service is the fact that it is very flexible and not limited to serving only customers having access to existing or readily installable cable plants. Moreover, there are many environments, such as, but not limited to portable data terminal equipments (DTEs), where a digital wireless subsystem may be the only practical means of communication. In order to provide digital telecommunication service, the wireless (radio) subsystem is interfaced with an existing digital network's infrastructure, which provides power, and legacy wireline links (that may contain one or more repeaters) to an incumbent service provider site.
As diagrammatically illustrated in FIG. 1, the radio itself employs an ISM-band compatible (e.g., spread spectrum) digital transceiver 10. The transceiver 10 includes a transmitter section 11, that is operative to perform spread spectrum modulation and up-conversion of baseband signals supplied from a baseband processor or digital data pump (such as a T1 framer chip) 15 coupled over a digital communication link 16 (e.g., a T1 link) to a telecommunication network 17.
The output of the transmitter section 11 is an FCC-conformal band RF signal (e.g., ISM 2.4-2.4385 GHz, or 5.725-5.850 GHz spread spectrum signal). This signal is applied to a transmit input port 21 of a diplexer 20, which has an antenna interface port 23 coupled to an associated radio antenna 25. A receiver output port 22 of the diplexer 20 is coupled to a receiver section 12 of the transceiver, in which the spread RF signal received from the remote site radio is down-converted and demodulated to baseband for application to the digital data pump 15.
The transmit and receive ISM band frequencies interfaced by the diplexer 20 with the antenna 25 are prescribed by one of two complementary frequency plans (e.g., a transmit frequency fT=2.462 GHz and a receive frequency fR=2.422 GHz for use by the local site radio). These frequencies correspond to those of a narrowband transmit path filter 26 installed between transmit port 21 and antenna port 23, and a narrowband receive path filter 27 installed between antenna port 23 and receive port 22. The other (complementary) frequency plan is employed by a companion digital radio at a remote site (e.g., having a transmit frequency fT=2.422 GHz and a receive frequency fR=2.462 GHz).
To facilitate selection of either frequency plan, the radio transceiver-diplexer arrangement may be configured as disclosed in the U.S. Patent to P. Nelson et al, U.S. Pat. No. 6,178,312, issued Jan. 23, 2001, entitled: “Mechanism for Automatically Tuning Transceiver Frequency Synthesizer to Frequency of Transmit/Receiver Filter” (hereinafter referred to as the '312 Patent), assigned to the assignee of the present application and the disclosure of which is incorporated herein. In accordance with this patented scheme, the frequency plan (transmit/receive frequency pair) of the radio is defined by selectively coupling the appropriate one of the two diplexer ports to the transmit port of the transceiver and the other diplexer port to the receive port of the transceiver. (At the far end or remote site the diplexer-to-transceiver port connections are reversed.)
Because the environment in which such a digital radio is expected to be used may not provide ready access to alternative communication services, resolving operational problems constitutes a significant challenge to the installer and user. For example, should an impairment or failure occur in initiating or conducting communications between the local radio and a remote site, it would be desirable to know if the problem is with the local radio site itself, or resides in the remote radio site. Also, at either site, feedline, connectors, the antenna itself, or the simple fact that that the link has not been properly ‘engineered’ can cause problems.